The play.api.libs.json package contains data structures for representing JSON data and utilities for converting between these data structures and other data representations. Some of the features of this package are:

Automatic conversion to and from case classes with minimal boilerplate. If you want to get up and running quickly with minimal code, this is probably the place to start.

Scala to JsValue conversion is performed by the utility method Json.toJson[T](T)(implicit writes: Writes[T]). This functionality depends on a converter of type Writes[T] which can convert a T to a JsValue.

The Play JSON API provides implicit Writes for most basic types, such as Int, Double, String, and Boolean. It also supports Writes for collections of any type T that a Writes[T] exists.

The \ operator returns a JsLookupResult, which is either JsDefined or JsUndefined. You can chain multiple \ operators, and the result will be JsUndefined if any intermediate value cannot be found. Calling get on a JsLookupResult attempts to get the value if it is defined and throws an exception if it is not.

You can also use the Direct lookup apply method (below) to get a field in an object or index in an array. Like get, this method will throw an exception if the value does not exist.

You can retrieve a value in a JsArray or JsObject using an .apply operator, which is identical to the Simple path \ operator except it returns the value directly (rather than wrapping it in a JsLookupResult) and throws an exception if the index or key is not found:

The simplest way to convert a JsValue to another type is using JsValue.as[T](implicit fjs: Reads[T]): T. This requires an implicit converter of type Reads[T] to convert a JsValue to T (the inverse of Writes[T]). As with Writes, the JSON API provides Reads for basic types.

The preferred way to convert from a JsValue to another type is by using its validate method (which takes an argument of type Reads). This performs both validation and conversion, returning a type of JsResult. JsResult is implemented by two classes:

JsSuccess: Represents a successful validation/conversion and wraps the result.